CZ280730B6 - Process for refining oil containing glycerides - Google Patents

Abstract

The invention relates to a method of refining glyceride oil comprising the step of degumming said glyceride oil, wherein said degumming step is followed by a separation step in which undissolved and non-centrifugable particles are removed from said degummed oil. Said degumming step is followed by a step of holding the degummed oil for such a period of time and under such temperature conditions as to cause agglomeration of said undissolved particles, and for an agent promoting the formation of undissolved particles and/or promoting the agglomeration of the undissolved particles is added to the oil.

Description

Process for refining triglyceride-containing oils

Technical field

The invention relates to a process for the refining of triglyceride-containing oils, in particular to a process for refining, one step of which consists in the dephosphatization.

BACKGROUND OF THE INVENTION

Oils containing triglycerides, especially of vegetable origin, for example soybean oil, rapeseed oil, sunflower oil, safflower oil, cottonseed oil and the like, are valuable raw materials in the food industry. These oils can be obtained in crude form usually from seeds and beans by compression and / or solvent extraction.

Said oils mainly consist of triglyceride components. However, they also contain a greater amount of other components including phosphatides (gummy or mucilaginous substances), waxy substances, partial glycerides, free aliphatic acids, dyes and also a small amount of metals. Depending on the intended use of the oil, these impurities may have an adverse effect on stability, especially on storage, on the taste and color of the resulting products. For this reason, refining is required in which phosphatides and other impurities are removed from the crude oils to the highest possible degree.

Usually, the first stage of refining glyceride oils consists of so-called mucus removal, i.e. phosphatide removal. By this term is meant any processing of the oil which results in the removal of mucilaginous substances and other components. In conventional processes of this type, water for hydrating the phosphatides is added to the triglyceride-containing crude oil, which is then removed, for example, by centrifugation. Since the resulting oil often still contains an unacceptably high amount of so-called non-hydratable phosphatides, it is usually necessary after this step to treat the oil chemically with acid and alkali to remove phosphatide residues and neutralize the free aliphatic acids (alkaline refining).

In the next step, the oil wastes which are suitable for making soap are separated from the neutralized oil by centrifugation. The resulting oil is then further refined by means of separation and deodorization processes.

After the above-described dephosphatidation with water, it is usually possible to obtain a residual amount of phosphorus of the order of 100 to 250 ppm. The improved process described in U.S. Pat. No. 4,049,686, wherein the crude or water-dephosphatidized oil is treated with a concentrated acid, particularly citric acid, can reduce the phosphorus residue up to a range of 20 to 50 ppm. It is therefore a better removal of phosphatides.

Usually, the lower the amount of phosphatides remaining after depletion of the mucilaginous oil, the better or easier the subsequent refining. Especially when the level of phosphatides is low, it is easier to carry out the step in which it is used

The base oil can then be further refined only by bleaching and steam refining. Non-alkali refining is often referred to as physical refining and is highly desirable in terms of environmental cleanliness, facilitation of the process and yields.

It has now been found that although the oil may appear to be crystal clear after removal of the mucilaginous components, it still contains some undissolved remaining parts, such as hydrated phosphatides, which cannot be removed by simple centrifugation, but these particles can be removed by direct microfiltration or any by other suitable separation after subjecting the dephosphatized oil to conditions that cause agglomeration and / or further precipitation of the undissolved phosphatides and the particles containing them, for example, the oil may be maintained at a suitable temperature for some time with the addition of agglomerating agents. If these residual phosphatides are removed, the amount of phosphorus remaining below 15 ppm and in some cases below 10 or even below 5 ppm can be achieved. A suitable method for removing this proportion of undissolved phosphatides, also suitable for technical scale, is microfilter filtration with a suitable orifice diameter and porosity.

It is an object of the present invention to provide new triglyceride-containing oils.

method of refining

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides a process for refining triglyceride-containing oils, wherein a mucilage-free oil is used, the oil is mixed with a chemical, and the mixture is maintained at a temperature of less than 40 ° C to form a particulate material. Separate, wherein the mucilaginized oil is mixed with an alkali in an amount equivalent to 0.01 to 100% of the free fatty acids present in the mucilaginized oil.

Essential for the refining according to the invention is the prior de-oiling of the oil containing mucilaginous triglycerides. This can be done by any conventional method including the hydration of phosphatides, it is desirable to reduce the amount of residual phosphorus to a level of 5 to 250 ppm.

Throughout the application, the term mucilaginisation refers to any process for the treatment of glyceride-containing oils in which water is added to the oil as such or with prior or subsequent or simultaneous addition of chemicals such as acids and / or bases such that at least part of % of the non-glyceride components, especially phosphatides, hydrate and then the insoluble hydrated material is separated by centrifugation or filtration to a residual phosphorus value of 5 to 250 ppm. Suitable processes for the removal of mucilaginous components are disclosed, for example, in British Patent Specification No. 1,565,569, U.S. Patent Nos. 4,240,972 and 4,276,227, and European Patent Publication No. 195,991.

In the simplest form of the process, a relatively small amount of water is added to the triglyceride-containing crude oil, 0.2 to 5, preferably 0.5 to 3% by weight, and then the sludge is removed

-2GB 280730 B6 containing phosphatides by centrifugation. This procedure is well known in the art and its description can already be found in textbooks.

An improved process has been described in U.S. Pat. No. 4,049,686. This process consists in dispersing an effective amount of concentrated acid or an anhydride thereof in a crude oil or optionally in an oil treated as described above, and then in the oil so treated. disperses an appropriate amount of water. The resulting water sludge is separated from the oil after heating the oil-acid-water mixture for at least 5 minutes to a temperature of not more than 40 ° C.

To reduce the amount of phosphorus up to a range of 20 to 50 ppm, the crude oil is preferably treated with a concentrated citric acid solution at 70 to 90 ° C for 10 to 20 minutes. Water is then added in an amount of 0.2 to 5%, preferably 0.5 to 3% by weight. Then the mixture is cooled either before or after the addition of water to a temperature below 40 ° C, preferably below 25 ° C. In order to ensure optimal hydration of the hydratable phosphatides in the oil, the mixture is maintained at this temperature for more than one hour, preferably 2 to 4 hours.

Depending on the amount of non-hydratable phosphatides, a certain amount of hydratable phosphatides as described in U.S. Pat. No. 4,162,260 may be added depending on the amount of non-hydratable phosphatides. The addition of hydrolyzed phosphatides as described in U.S. Pat. No. 4,584,141. The phosphatide-containing sludge is then removed from the oil by centrifugation. It is preferable to heat the mixture to 50-80 ° C just prior to centrifugation.

After this step (including sludge removal), the oil is further processed to remove the remaining fraction of undissolved phosphatides that are present as very small particles with a diameter below 0.05 to 10 microns depending on the separation process and its conditions.

A suitable and preferred method for removing phosphatide residues is to filter the oil through a microfilter with a suitable pore diameter.

Thus, the process of the invention consists in filtering glyceride-containing oils after removal of the mucilaginous oil components through a microfilter with an average pore diameter suitable to reduce the phosphorus residue below 15 ppm.

In order to reduce the phosphorus to this level, the filter apertures should have a diameter below 5 microns. A further advantageous reduction of the phosphorus content below 10 or up to 5 ppm can be achieved by using a microfilter whose apertures have an average diameter below 0.5 microns, preferably in the range of 0.1 to 0.3 microns.

Agglomeration can be initiated and / or increased by subjecting the oil to conditions where particles of material that do not dissolve in the oil or the particles of the undissolved particles are agglomerated, such as lowering the temperature or adding agents that promote particle formation and / or promote agglomeration of insoluble particles. Examples of such substances are bases (hydroxide

Potassium, sodium hydroxide, sodium silicate, calcium carbonate), acids such as phosphoric, citric, tartaric and the like, hydratable phosphatides of U.S. Pat. No. 4,162,260 or hydrolyzed phosphatides of U.S. Pat. No. 4,584 141. With respect to the addition of a base, an amount equivalent to 0.01 to 100% of the aliphatic acids present in the deionized oil may be added. Preferably, an amount equivalent to 0.05 to 50% of the free aliphatic acids in the oil is added. Depending on the addition of these agents and the agglomeration time, the temperature may be selected or the agglomeration time may be shortened at certain selected temperatures.

Optionally, the separation step may include the addition of absorbent for undissolved particles having adsorbent agents may be bleached or activated carbon materials containing arbocel. oxides of it or adsorbing agent can be removed. An example of clay, hemi-cellulose-containing materials, for example, may be microporous e.g. Trisyl.

Examples of silicon and aluminosilicate absorbents,

Further measures which favor the agglomeration may be further removal or any other separation process to remove undissolved particulate material from the oil.

Advantageously, an improved process for removing mucilaginous components is used, since it is possible to reduce the agglomeration time and also to use higher temperatures. Preferably, the agglomeration is carried out at the same temperature as the removal of the mucilaginous components.

Undissolved particles or agglomerates can be removed by filtration, microfiltration, centrifugation, settling and decantation. After removal of the particles, refining of the oil having a phosphorus content of, for example, below 15 ppm, preferably below 10 ppm or even below 2 or 5 ppm, can be continued using any refining process to provide the desired parameters of the resulting oil. For example, alkaline refining, bleaching and odor removal can be used.

The low phosphorus content below 10 to less than 5 ppm, which can be achieved by the process of the invention, has a beneficial effect on the consumption of bleaching agents, which increases refining efficiency and reduces environmental pollution when the bleach consumption is too high.

The following examples illustrate the process according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Crude maize germ oil is freed from mucilaginous constituents as follows:

-4GB 280730 B6

1) The crude oil is mixed with 0.07% citric acid monohydrate (as a 50% solution) at 85 ° C,% water, allowed to hydrate for a total of 20 minutes.

C a

4) the mixture is cooled for 3 hours, then the sludge is separated from the centrifuge.

to 25 with oils at a temperature of ° C using a separator

Then the resulting filtering on five ranged from 1.20 to the results:

Oil free, 0.22 micron microfilter.

The following residual phosphorus in ppm after phosphatide removal has been achieved,

without filtration 21.6 filter with 1.20 micrometer holes 15.2 filter with 0.80 micrometer holes 16.6 filter with 0.65 micrometer holes 14.3 filter with 0.45 micrometer holes 8.9 filter with 0.22 micrometer holes 6.7

Example 2

Crude rapeseed oil was freed from the mucilaginous components as follows:

(1) 2% of hydrolysed lecithin and 0,12% citric acid monohydrate as a 50% solution are added to the crude oil at 65 ° C;

2) 1.7% water was added after 20 minutes,

3) the mixture was cooled to 40 ° C, hydrating for a total of 3 hours, then

4) the sludge was removed from the oil at a temperature of 65 ° C using a separating centrifuge.

Microfiltration was then performed using five Milipore filters with openings ranging from 1.20 to 0.22 microns. The following results were achieved:

residual phosphorus in ppm after removal of phosphatides, without filtration 20

filter with holes 1.20 micrometers 10 filter with holes 0.80 micrometers 7 filter with holes 0.65 micrometers 8 filter with holes 0.45 micrometers 5 filter with holes 0.22 micrometers 4

-5GB 280730 B6

For comparison, the same filtration was carried out using rapeseed oil which was not depleted of mucilaginous constituents and oil which had been depleted of mucilaginous constituents but was then dried, which means that it contained the remaining phosphatides only in unhydrated form. The following results were achieved:

residual phosphorus in ppm without de-phosphatization with de-phosphatization and drying

without filtration 410 18 filter with 1.20 micrometer holes 430 18 filter with 0.65 micrometer holes 410 17 filter with 0.22 micrometer holes 420 17

These comparisons clearly show that the microfiltration according to the invention can only be successfully applied to oil which is free of mucilaginous constituents and still contains residual particles, for example phosphatides. Upon the addition of water, undissolved particles were formed which could be removed by microfiltration as in the first five experiments mentioned above.

Example 3

The crude oil was freed from the mucilaginous components by the method of Example 2. Sodium hydroxide was then added in an amount equivalent to either 15 or 25% of the free aliphatic acids present in the oil, i.e. 0.19 and 0.32%. Sodium hydroxide was thoroughly mixed with mucilaginized rapeseed oil.

After 3-4 hours, the oil samples were filtered using filters with 8, 1.2 and 0.4 micron diameter.

The results of two independent experiments are summarized in the following table.

addition of a base without a base the remaining phosphorus (ppm) after 3-4 hours.

without 8 μπι 1,2 μιη 0,4 μιη filtration up to 9 4 to 3 to 6,0 3,5 to 5,5 2,1 to 3,3 equiv. 15% acid 8

2.7

2.1 0.4 equiv. 25% acid 10

5.2

3.9

-6GB 280730 B6

Example 4

Crude rapeseed oil was freed from the mucilaginous components in a manner similar to Example 2. After the addition of alkali and standing time of 3-4 hours at room temperature (less than 30 ° C), the separation step was carried out using a clarifying apparatus (Westfalia SAOOH 205) at a conventional reflux pressure and different flow. The results are summarized in the following table.

The table shows that the remaining, undissolved and initially non-centrifugable particles, such as phosphatides, can be effectively removed by centrifugation with the addition of a base.

Explanatory notes to the table:

adg conditions for removal of mucilaginous substances, inlet temperature up to 85 ° C, P-content of phosphorus in the feed oil 1000 to 1100 ppm with 2.2% hydrolysed lecithin, addition of citric acid monohydrate, 0.12%, 0.12% added water

2.2%, hydration time 3 hours, separation temperature 65 ° C.

The increase in baseline resistance in experiments II and II was due to contamination of the clarifier.

Attempt conditions amount left over alifa- Fe Ca / Mg / Na No. (sgd) a added phosphorus tické (ppm) (ppm) flow policy in% (ppm) kyseli- 1 / h acid % (%)

AND initial content P after sdg 0 7.0 5 0 4.0 13 0 4.4 25 0 4.9 30 0 4.2 II initial content P after sdg 15 Dec 7.7 0.88 0.1 1.3 / 0.6 / 140 7 15 Dec 1.0 0.81 <0.1 0.3 / 0.1 / 4.3 17 15 Dec 1.9 0.83 <0.1 0.2 / 0.1 / 7.9 63 15 Dec 0.7 0.83 <0.1 0.3 / 0.3 / 9.3 III initial content P after sdg 25 10.3 23 25 0.7 0.78 0.4 1.3 / 0.4 / 16 40 25 2,0 0.78 0.4 1.0 / 2.2 / 13 105 25 1.4 0.80 0.3 0.9 / 0.2 / 6.5 125 25 1,2 0.75 1.0 0.9 / 0.2 / 33

-7EN 280730 B6

Example 5

Crude rapeseed oil was stripped degumming as in Experiment III from Example 4. The undissolved now agglomerated particles were removed by microfiltration (filter Micorza Asahi, filter surface ^of 0.2 m).

The results are shown in the table.

oil properties before microfiltration residual phosphorus (ppm) 16.4 free aliphatic acid (%) 0.92

Ca / Mg (ppm) 5.3 / 1.5

Fe (ppm) 1.3

Na (ppm) 610 after microfiltration

2,0

0.76

0.5 / 0.2

Claims (7)

PATENT CLAIMS A process for refining triglyceride-containing oils, wherein a mucilage-free oil is used, the oil is mixed with a chemical, and the mixture is maintained at a temperature below 40 ° C to form a particulate material and the material is then separated characterized in that the mucilaginized oil is mixed with an alkali in an amount equivalent to 0.01 to 100% of the free fatty acids present in the mucilaginized oil. The process according to claim 1, characterized in that the base is added in an amount equivalent to 0.05 to 50% by weight of free fatty acids in the slime-free oil. Process according to claim 1 or 2, characterized in that the base is selected from sodium hydroxide, sodium silicate and calcium carbonate. Method according to one of Claims 1 to 3, characterized in that it is based on triglyceride oil which has been completely free of mucilaginous substances. 5. Method according to of claims 1 to 4, you from us C and s e by that is mixture maintains on temperature below 40 "C Ρθ time 0,5 to 5 hours • 6. Method according to of claims 1 to 5, you from us C and s e by that is for easier creation particle material and / or adds an agent to the oil to promote agglomeration of the insoluble particles. -8EN 280730 B6 7. The method of claim 6, wherein the agent is selected from hydrolyzed phosphatides characterized by a group of hydratable phosphatides, and mixtures thereof. Method according to one of Claims 1 to 7, characterized in that an adsorption agent for the undissolved particles to be removed is added when separating the particulate material. Method according to claims 1 to 8, characterized in that the particles are separated by filtration, microfiltration, centrifugation, sedimentation and / or decantation. Method according to claims 1 to 9, characterized in that the mixture is heated to a temperature of 50 to 80 ° C before the particles are separated.